Presentation to North Sydney community on Westconnex Dr Michelle Zeibots MPIA CMILT

Research Director, UTS Transport Research Centre  

1.  Induced traffic growth 2.  Impact on road network congestion 3.  History of F1 motorway 4.  Westconnex and the big picture

Induced traffic growth

The  following  slides  provide  an  example  of  what  transport  planners  and  traffic  engineers  call  induced  traffic  growthˆ  –  the  addi8onal  traffic  that  is  generated  by  new  road  or  motorway  that  makes  traffic  speeds  quicker.    This  example  shows  the  posi8on  of  the  last  missing  link  in  the  M4  Motorway  from  Mays  Hill  to  Prospect  that  was  opened  to  traffic  in  1992.  AGer  opening  the  combined  traffic  volumes  on  the  M4  and  parallel  arterial  the  Great  Western  Highway  were  suddenly  higher  by  almost  20,000  addi8onal  vehicle  movements  on  average  per  day.    Where  did  this  addi8onal  traffic  come  from?    Further  analysis  shown  that  some  was  traffic  that  shiGed  from  road  as  far  away  as  Windsor  and  Richmond  Roads  in  the  north  and  Elizabth  Drive  and  Bringelly  Road  in  the  south.  But  even  when  taking  all  other  possible  road  op8ons  into  account,  there  is  s8ll  a  residual    volume  of  about  11,000  average  vehicle  movements  per  day  that  cannot  be  accounted  for.  

M4 Motorway link in Sydney

M4  Mays  Hill  to  Prospect  15  May  1992  

M4 Motorway &Great Western Hwy

Annual average daily traffic on M4 Motorway & Great Western Hwy

Opening of motorway section(15 May 1992)

M4 monitoring site

GWH monitoring site

Opening  of  Mays  Hill  to  Prospect  M4  sec8on  (15  May  1992)  

Induced traffic growth When  we  examine  changes  to  passenger  journey  numbers  on  the  parallel  Western  Sydney  Rail  Line,  we  find  reduc8ons  of  about  6,000  journeys  on  average  per  day.  But  this  s8ll  leaves  around  5,000  addi8onal  vehicle  movements  that  cannot  be  accounted  for.    This  appears  to  be  people  choosing  to  make  addi8onal  trips  —  induced  trips  —  or  travelling  to  places  that  are  further  away  than  their  usual  des8na8ons  —  traffic  redistribu5on.    On  many  of  these  parallel  arterial  roads  traffic  volumes  returned  top  what  they  were  before  the  M4  addi8on  with  a  few  years.    The  pa]ern  of  responses  in  this  example  can  be  observed  in  all  cases  where  urban  road  capaci8es  are  expanded.  It  has  generally  been  observed  that  induced  traffic  growth  rates  are  higher  networks  where  conges8on  levels  are  highest.    It  is  caused  by  people  wan8ng  to  take  advantage  of  quicker  travel  8mes.  In  these  cases  people  con8nue  to  join  the  network  or  make  more  trips  un8l  travel  8mes  return  to  what  they  were  before  the  motorway  opening  where  there  are  no  further  travel  8me  advantages.  

Impact on road traffic congestion

This  raises  the  ques8on  —  what  should  we  do  and  what  effect  would  building  a  further  motorway  extension  to  the  northern  beaches  achieve?    By  looking  at  what  happened  when  the  Sydney  Harbour  Tunnel  was  opened  to  traffic  in  1992,  we  can  see  some  similar  results  to  the  M4  example  —  traffic  shiGing  from  the  deck  of  the  Harbour  Bridge  to  the  new  faster  route  via  the  Sydney  Harbour  Tunnel  and  combined  volumes  that  reveal  an  increase  in  traffic  known  as  the  ramp  up  period  that  is  higher  than  previous  volumes.    What  we  can  also  see  is  that  traffic  volumes  on  the  deck  of  the  bridge  had  stabilised  at  about  180,000  vehicle  movements  on  average  per  day  from  about  1986  un8l  1992.  This  ‘stable’  volume  provides  an  example  of  a  road  opera8ng  at  full  capacity,  or  what  traffic  engineers  call  Level  Of  Service  E.    In  the  following  slide  you’ll  see  a  table  that  describes  what  traffic  conges8on  levels  are  like  at  different  volumes  ranging  from  Level  Of  Service  A  (which  is  free  and  easy)  to  Level  Of  Service  F  (which  represents  chronic  conges8on).  

Source:  M4  East  Environmental  Impact  Statement:  Appendices  A–G  Volume  2A  —  Appendix  G:  traffic  and  transport  assessment.  NSW  Government,  Sydney,  p.  1-­‐2.  

Sydney  Harbour  Bridge  opera8ng  at  Level  Of  Service  E  (1986–1991)  

Impact on road traffic congestion There  are  two  significant  points  that  come  from  this  example.    (1)  This  case  provides  an  evidence  based  example  of  how  traffic  engineers  assess  and  measure  road  traffic  conges8on  —  through  Level  Of  Service  grades  (A-­‐F)  based  on  observa8ons  of  traffic  volume  throughputs  and  limits.    (2)  Many  of  the  road  intersec8ons  alongside  the  newly  proposed  Westconnex  motorway  sec8ons  are  experiencing  conges8on  at  Level  Of  Service  F.  The  official  traffic  modeling  for  the  project  shows  that  most  of  these  will  con8nue  to  operate  at  Level  Of  Service  F  aGer  Westconnex  is  brought  into  opera8on.    This  raises  the  ques8on  —  if  official  models  are  showing  only  minor  improvements  then  why  are  we  building  these  motorways?  Can  we  really  jus8fy  spending  tens  of  billions  of  dollars  of  public  money  for  li]le  or  not  improvement?  Is  this  why  the  economic  benefit  calcula8ons  have  never  been  made  public?    A  more  construc8ve  ques8on  to  ask  is  —  if  we  don’t  build  motorways,  what  should  we  build  instead  and  why?  What  op8ons  are  there  that  will  genuinely  benefit  our  community?  

The role of public transport

Many  residents  and  speakers  at  this  community  mee8ng  organised  through  North  Sydney  Council  on  Westconnex  made  the  point  or  raised  the  ques8on  —  what  can’t  we  build  a  train  line  instead?    While  I  cannot  answer  ques8ons  around  the  poli8cs,  I  can  answer  ques8ons  around  what  the  effect  on  traffic  would  be  if  a  substan8al  public  transport  line  were  built  —  a  major  train  line  to  serve  the  sector  much  like  those  in  all  the  other  sectors  of  Sydney  and  soon  the  North  West  of  Sydney  with  the  opening  of  the  new  Metro  line.    Poten8ally,  road  traffic  speeds  would  be  liGed.    How  and  why  this  would  happen  is  explained  on  the  next  slide.  But  the  important  point  to  make  here  is  that  in  ci8es  all  over  the  world  as  well  as  in  Sydney,  road  speeds  appear  to  be  largely  determined  by  public  transport  speeds.  This  is  because  the  vast  majority  of  people  make  transport  decisions  based  on  whichever  op8on  is  quickest.  

The ‘functional balance’ between public & private transport

1.  Public transport operates to a fixed speed — a timetable.

2.  Roads operate to variable speeds determined by car numbers — congestion.

3.  Most people will take whichever transport option is quickest. If public transport is quicker, they'll catch a train or bus, and the number of people won’t change the speed.

4.  If driving is quicker, people will use their car. The more who do, the slower the road network becomes.

5.  People who shift between modes in pursuit of the quickest option are the reason why public transport speeds determine road speeds.

County of Cumberland Scheme

Business Centres

Special Uses Areas

County Centre

ZONING

Living Areas

Green beltOpen spaceparks etc.

COMMUNICATIONS

National and Regional Roads

Railways

0 1 2 3 4 5 10

Scale of Miles

Bondi

Manly

BotanyBay

Riverstone

Windsor

Broken Bay

Palm Beach

Bulli

Campbelltown

Liverpool

Penrith St Marys

Richmond

Cronulla

Industrial Areas

Rural Areas

Camden

M4

M5

M2M1

M6

F3

Impact of the Northern Beaches Motorway link A  motorway  to  the  Northern  Beaches  is  not  a  new  idea.  It  was  first  raised  in  the  late  1940s  before  being  incorporated  into  the  legisla8ve  plan  known  as  the  County  of  Cumberland  Scheme  in  1952.    In  the  late  1970s  a  Commission  of  Inquiry  into  the  F1  found  it  should  not  be  built,  primarily  for  reasons  to  do  with  induced  traffic  growth  outlined  earlier.    Back  in  the  1940  and  50s  we  didn’t  know  as  much  about  the  real  effects  of  motorway  development  on  urban  transport  networks.    If  the  Northern  Beaches  motorway  link  is  built  it  will  funnel  more  road  traffic  into  the  centre  of  a  more  extensive  congested  urban  motorway  network.  In  ci8es  where  motorway  networks  have  been  completed  so  that  they  are  more  ‘connected’  like  the  M25  orbital  motorway  in  London,  the  nature  of  conges8on  is  now  worse  with  the  advent  of  ‘superjams’  —  traffic  jams  that  can  last  for  4,  6  up  to  8  hours  at  a  8me.    Condi8ons  like  this  are  now  more  frequent  on  the  network  around  the  Airport  where  the  M5  and  other  motorways  all  meet.  

Proposed motorway network